Inflatable antenna assembly



SEARCH Oct. 24, 1961 K. M. MACK ET AL 3,005,987

INFLATABLE ANTENNA ASSEMBLY Filed Feb. 19, 1957 INVENTORS James W. Currie ,Stunley H. Soulson and Kent M. Muck. ?%2/ ATTORNEY WITNESSES United States Patent 3,005,987 INFLATABLE ANTENNA ASSEMBLY Kent M. Mack, North Linthicum, and James W. Currie and Stanley H. Saulson, Baltimore, Md, assignors to Westinghouse Electric Corporation, East Pittsburgh,

Pa, a corporation of Pennsylvania Filed Feb. 19, 1957, Ser. No. 641,439 11 Claims. (Cl. 343-872) This invention relates to an extremely lightweight antenna assembly and more particularly to an inflatable antenna structure which may be deflated and packed in shipping containers of small volume.

It is an object of this invention to provide a new and improved lightweight antenna assembly.

More specifically, an object of the invention is to provide an inflatable fabric antenna which provides a maximum antenna reflector surface with a minimum amount of required fabric.

A still further object of the invention is to provide an antenna assembly in which the antenna reflector is formed by partially evacuating an enclosure which has at least one side formed from flexible material, the arrangement being such that the flexible material will assume the configuration of a curved surface when the enclosure is evacuated.

The above and other objects and features of the invention will become readily apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification and, in which:

FIGURE 1 is an overall perspective view of the invention; and

FIG. 2 is a cutaway view of the antenna of the assembly shown in FIG. 1.

Referring to FIGS. 1 and 2, there is shown a tripod base which carries for rotation an upright tubular shaft 12. Carried on shaft 12 is an inflatable antenna 14 which comprises an elliptical tubular member 16 having sheets of flexible non-conducting material 18 and 20 fastened to its opposite sides to define an enclosure. When member 16 is inflated, it will inherently assume a more or less annular configuration. To form the tube into an ellipse, lacing 22 is fastened to the inner peripheral surface of the tube to compress it in one direction and elongate it in the other. The enclosure defined by sheets 18 and 20 and the inner peripheral surface of tubular member 16 is partially evacuated (i.e., the pressure within the enclosure is lower than the surrounding pressure) so that the sheets 18 and 20 will form concave surfaces, substantially as shown in FIG. 2. The outer surface of one of the sheets 18 is provided with a coating of wave energy reflective material 24, such as vaporized aluminum, to form an antenna reflector. The antenna is bowed by a pair of non-conducting stringers 26 and 28 which extend between opposite ends of the elliptical antenna. In this way the concave surface of one of the sheets 18- and the bow produced by the stringers 26 and 28 cause the antenna reflector 24 to assume the configuration of a paraboloid. As will be understood, lashing or other suitable fastening means, not shown, may be employed to secure the antenna 14 to shaft 12.

A feed horn 30* is positioned in front of the reflector 24 and is connected through a wave guide in shaft 12 to radar electronic apparatus carried in a transportable panel rack 32. Among the various electronic equipment carried in rack 32, there is a removable chassis 34 which carries the radar scope. The chassis may be pulled out of the rack and placed in a position remote from the antenna, with cables connecting the chassis to the remainder of the equipment. Also included in the rack is Patented Oct. 24, 1961 a small power supply 38 which may be separated from the rack and placed at a point remote from the antenna.

As will be understood, the antenna itself is highly vulnerable to high winds and ice loads which may distort its parabolic configuration. To protect the antenna and prevent distortion, there is provided a doughnut-shaped radome 40 which completely envelops the antenna. As shown, the radome comprises a toroidal balloon formed from flexible non-conducting fabric. The radome is fastened to shaft 12 so that its central axis is substantially coincident with the axis of shaft 12. In this manner the radome is entirely symmetrical about the axis of shaft 12 and is best able to withstand high winds. A small induction motor *41 or other suitable means is provided to rotate shaft 12, the antenna 14, and radome 40 to impart scanning motions to the antenna.

Means, not shown, are provided to maintain the pressure within the radome 40 above the surrounding at mospheric pressure and to maintain the pressure within the enclosure defined between sheets 18 and 20 below the pressure in the radome so that the sheets assume their curved configuration. Since the entire antenna assembly, except for reflector 24, is formed from non-conductive material, it is essentially transparent to radio frequency energy and will not obstruct radio waves which impinge upon the reflector.

Although the invention has been shown in connection with a certain specific embodiment, it should be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the sprit and scope of the invention.

We claim as our invention:

1. An inflatable parabolic antenna comprising an endless inflatable tube Which is generally elliptical in configuration when inflated, a pair of generally elliptical sheets of flexible non-conducting material fastened at their peripheries to opposite sides of said tube to form an enclosure to contain air at a pressure, below the surrounding pressure whereby the flexible sheets will form concave surfaces extending inwardly of such enclosure, and wave energy reflective material fixed to the surface of one of said sheets.

2. An inflatable parabolic antenna comprising an endless inflatable tube Which is generally elliptical in configuration when inflated, a pair of generally elliptical sheets of flexible non-conducting material fastened to the opposite sides of said tube to form an enclosure, means for maintaining an air pressure differential between the interior and exterior of said enclosure whereby the flexible sheets will form curved surfaces, and wave energy reflective material carried on the surface of one of said sheets.

3. An inflatable antenna comprising an endless inflatable tube, a pair of sheets of flexible non-conducting material fastened at their peripheries to opposite sides of said tube to form an enclosure, means for maintaining air pressure within said enclosure below the surrounding pressure whereby the flexible sheets will form concave surfaces extending inwardly of such enclosure, and wave energy reflective material carried on the surface of one of said sheets.

4. An inflatable antenna comprising an endless tube, sheets of flexible material fastened to opposite sides of said tube to form an enclosure containing air at a pressure below the surrounding pressure, and wave energy reflective material carried on the surface of one of said sheets.

5. An antenna structure comprising an outer rim member which is generally elliptical in configuration, a pair of generally elliptical sheets of flexible non-conducting material fastened at their peripheries to opposite sides of said rim member to form an enclosure to contain air at a pressure below the the surrounding pressure whereby the flexible sheets will form concave surfaces extending inwardly of such enclosure, and wave energy reflective material fixed to the outer surface of one of said sheets.

6. An inflatable parabolic antenna comprising an endless inflatable tube, means for forcing said tube to assume a generally elliptical configuration, a pair of generally elliptical sheets of flexible material fastened at their peripheries to opposite sides of said tube to form an enclosure to contain air at a pressure below the sur rounding pressure whereby the flexible sheets will form concave surfaces extending inwardly of such enclosure, means for forcing said tube and its associated flexible sheets to curve whereby one of said sheets will form a parabolic surface, and wave energy reflective material fixed to the surface of the one said sheets which is parabolic in configuration.

7. In an antenna system, a base member, an upright shaft carried for rotation by said base member, an inflatable parabolic antenna carried by said shaft and comprising an endless inflatable tube which is generally elliptical in configuration when inflated, a pair of generally elliptical sheets of flexible non-conductive material fastened at their peripheries to opposite sides of said tube to form an enclosure containing air at a pressure below the surrounding pressure whereby the flexible sheets will form concave surfaces extending inwardly of such enclosure, and wave energy reflective material fixed to the surface of one of said sheets.

8. In an antenna system, a collapsible base member, an upright shaft carried for rotation by said base member, an inflatable parabolic antenna carried by said shaft and comprising an endless inflatable tube which is generally elliptical in configuration when inflated, a pair of generally elliptical sheets of flexible non-conducting mate rial fastened at their peripheries to opposite sides of said tube to form an enclosure, means for maintaining a pressure differential between the interior and exterior of said enclosure whereby the flexible sheets will form curved surfaces, wave energy reflective material fixed to the outer surface of one of said sheets, a wave energy feed mechanism for directing radio frequency energy toward said reflective material, and means for rotating said upright shaft member to impart scanning motions to said antenna.

9. In an antenna system, a base member, an upright shaft member, an inflatable parabolic antenna carried by said shaft and comprising an endless inflatable tube which is generally elliptical in configuration, sheets of flexible non-conducting material fastened at their peripheries to opposite sides of said tube to form an enclosure containing a compressible fluid medium at a pressure different than the pressure at the exterior of said enclosure, wave energy reflective material carried on the surface of one of said sheets, and an inflatable toroidal radome surrounding said inflatable antenna and carried by said rotatable shaft such that the axis of the toroidal radome is substantially coincident with the axis of said shaft.

10. In an antenna system, a base member, an upright shaft carried for rotation by said base member, an inflatable antenna carried by said shaft and comprising an endless inflatable tube, sheets flexible non-conducting material fastened to opposite sides of said tube to form an enclosure at a pressure different than that at its exterior whereby the flexible sheets will form curved surfaces, wave energy reflective material fixed to the outer surface of one of said sheets, and an inflatable radome of flexible non-conducting material carried by said shaft for enveloping said antenna.

11. In an antenna system, a tripod base member, an upright shaft carried by said base member for rotation thereon, an inflatable parabolic antenna reflector carried by said shaft, and an inflatable radome of flexible non-conducting material carried by said shaft for enveloping said antena reflector, said reflector being generally elliptical in configuration and said radome being generally toroidal in configuration and fastened to said shaft in a manner such that the axis of said shaft is substantially concident with the axis of the toroidal radome.

References Cited in the file of this patent UNITED STATES PATENTS 1,615,755 Graue Jan. 25, 1927 2,460,274 Beniofl Feb. 1, 1949 2,463,517 Chromak Mar. 8, 1949 2,814,038 Miller Nov. 19, 1957 2,842,767 Darrouzet July 8, 1958 2,913,726 Currie et al. Nov. 17, 1959 OTHER REFERENCES Pub. 1., Radically New Radar Antenna Inflates Like Ballon, Aviation Week, Oct. 22, 1956, pages 94, 95, 97, 98. 

